Kaku explains Einstein's revolutionary insight that gravity is not a pulling force but rather the effect of mass bending the fabric of space, using the analogy of a fat actor warping a trampoline stage. He describes how string theory extends this into 10 and 11 dimensions, with the latest M-theory suggesting that our entire universe exists on the surface of a bubble in a boiling multiverse where Big Bangs happen constantly. The discussion covers wormholes as shortcuts through space, the Casimir effect as laboratory evidence of negative energy, and the hypothetical negative matter that could serve as fuel for a time machine. Kaku outlines the Kardashev scale of civilizations, classifying humanity as a primitive Type 0 that burns dead plants for energy, roughly 100 to 200 years from achieving Type 1 planetary status.
Art challenges Kaku on whether advanced civilizations would necessarily be peaceful, and Kaku responds with the sobering observation that the real danger lies in whether Type 0 civilizations can survive their own nuclear weapons and pollution long enough to evolve.
Key Moments
String theory, 10D hyperspace, and 11D M-theory: Kaku lays out the latest physics: string theory holds that gravity exists in 10-dimensional hyperspace; the new M-theory works in 11 dimensions with membranes and pulsating bags. Harvard, Princeton, and Columbia are now awarding tenure to hyperspace physicists.
Wormholes - Sagan's 'Contact' and the trapdoor: Kaku describes wormhole physics: a trap door drilled through the 'stage' of spacetime. Carl Sagan, a former friend now passed, drew his Contact mechanism from these conversations with Kaku and other physicists. The energy required is Type II or III civilization scale.
12 black holes seen - one at the center of the Milky Way: Kaku reports that 12 black holes have now been observed in space; the Milky Way itself harbors a black hole at its center, only about 30,000 light years away, while the others sit roughly 30 million light years out.
Negative energy and the Casimir effect: Kaku says negative energy is no longer laughable: the Casimir effect, in which two uncharged parallel metal plates measurably attract each other with a force much greater than gravity, is well confirmed in laboratories - and could in principle stabilize a wormhole.
Kardashev scale - we are Type 0: Kaku introduces Russian astrophysicist Nikolai Kardashev's civilization scale: Type I harnesses a planet's energy, Type II a star, Type III a galaxy. Earth is Type 0 - we still burn dead plants. He estimates we are 100 to 200 years from Type I.